From b80289403777a1f7664ce83688fd7e64b68a820f Mon Sep 17 00:00:00 2001
From: Adrian <78108584+AdrianCassar@users.noreply.github.com>
Date: Tue, 20 Aug 2024 21:28:18 +0100
Subject: [PATCH] Implemented: MD5 guest functions

---
 src/xenia/kernel/xboxkrnl/xboxkrnl_crypt.cc | 99 +++++++++++++++++++++
 1 file changed, 99 insertions(+)

diff --git a/src/xenia/kernel/xboxkrnl/xboxkrnl_crypt.cc b/src/xenia/kernel/xboxkrnl/xboxkrnl_crypt.cc
index 812d1e035..309044514 100644
--- a/src/xenia/kernel/xboxkrnl/xboxkrnl_crypt.cc
+++ b/src/xenia/kernel/xboxkrnl/xboxkrnl_crypt.cc
@@ -29,6 +29,7 @@
 #include "third_party/crypto/sha256.h"
 
 extern "C" {
+#include "third_party/FFmpeg/libavutil/md5.h"
 #include "third_party/FFmpeg/libavutil/sha512.h"
 #include "third_party/aes_128/aes.h"
 }
@@ -168,6 +169,33 @@ void XeCryptSha_entry(lpvoid_t input_1, dword_t input_1_size, lpvoid_t input_2,
 }
 DECLARE_XBOXKRNL_EXPORT1(XeCryptSha, kNone, kImplemented);
 
+void XeCryptMd5_entry(lpvoid_t input_1, dword_t input_1_size, lpvoid_t input_2,
+                      dword_t input_2_size, lpvoid_t input_3,
+                      dword_t input_3_size, lpvoid_t output,
+                      dword_t output_size) {
+  AVMD5* md5 = av_md5_alloc();
+  av_md5_init(md5);
+
+  if (input_1 && input_1_size) {
+    av_md5_update(md5, input_1, input_1_size);
+  }
+
+  if (input_2 && input_2_size) {
+    av_md5_update(md5, input_2, input_2_size);
+  }
+
+  if (input_3 && input_3_size) {
+    av_md5_update(md5, input_3, input_3_size);
+  }
+
+  uint8_t digest[16];
+  av_md5_final(md5, digest);
+
+  std::copy_n(digest, std::min<size_t>(xe::countof(digest), output_size),
+              output.as<uint8_t*>());
+}
+DECLARE_XBOXKRNL_EXPORT1(XeCryptMd5, kNone, kImplemented);
+
 // TODO: Size of this struct hasn't been confirmed yet.
 typedef struct {
   xe::be<uint32_t> count;     // 0x0
@@ -299,6 +327,77 @@ void XeCryptSha512Final_entry(pointer_t<XECRYPT_SHA256_STATE> sha_state,
 }
 DECLARE_XBOXKRNL_EXPORT1(XeCryptSha512Final, kNone, kImplemented);
 
+// TODO: Size of this struct hasn't been confirmed yet.
+typedef struct {
+  xe::be<uint64_t> count;
+  xe::be<uint32_t> state[4];
+  uint8_t buffer[64];
+} XECRYPT_MD5_STATE;
+
+void XeCryptMd5Init_entry(pointer_t<XECRYPT_MD5_STATE> md5_state) {
+  md5_state.Zero();
+
+  // must match av_md5_init
+  md5_state->state[0] = 0x10325476;
+  md5_state->state[1] = 0x98badcfe;
+  md5_state->state[2] = 0xefcdab89;
+  md5_state->state[3] = 0x67452301;
+}
+DECLARE_XBOXKRNL_EXPORT1(XeCryptMd5Init, kNone, kImplemented);
+
+struct MD5_STATE {
+  uint64_t len;
+  uint8_t block[64];
+  uint32_t ABCD[4];
+};
+
+void XeCryptMd5Update_entry(pointer_t<XECRYPT_MD5_STATE> md5_state,
+                            lpvoid_t input, dword_t input_size) {
+  AVMD5* md5 = av_md5_alloc();
+  av_md5_init(md5);
+
+  // Trick to make similar implementation as SHA256
+  MD5_STATE* md5InternalState = reinterpret_cast<MD5_STATE*>(md5);
+  std::copy(std::begin(md5_state->state), std::end(md5_state->state),
+            md5InternalState->ABCD);
+  std::copy(std::begin(md5_state->buffer), std::end(md5_state->buffer),
+            md5InternalState->block);
+  md5InternalState->len = md5_state->count;
+
+  // Add new entry from input
+  av_md5_update(md5, input, input_size);
+
+  // Copy back data to guest md5_state
+  std::copy_n(md5InternalState->ABCD, xe::countof(md5_state->state),
+              md5_state->state);
+  std::copy_n(md5InternalState->block, xe::countof(md5_state->buffer),
+              md5_state->buffer);
+  md5_state->count = md5InternalState->len;
+}
+DECLARE_XBOXKRNL_EXPORT1(XeCryptMd5Update, kNone, kImplemented);
+
+void XeCryptMd5Final_entry(pointer_t<XECRYPT_MD5_STATE> md5_state,
+                           pointer_t<uint8_t> out, dword_t out_size) {
+  AVMD5* md5 = av_md5_alloc();
+  av_md5_init(md5);
+
+  // Trick to make similar implementation as SHA256
+  MD5_STATE* md5InternalState = reinterpret_cast<MD5_STATE*>(md5);
+  std::copy(std::begin(md5_state->state), std::end(md5_state->state),
+            md5InternalState->ABCD);
+  std::copy(std::begin(md5_state->buffer), std::end(md5_state->buffer),
+            md5InternalState->block);
+  md5InternalState->len = md5_state->count;
+
+  uint8_t hash[16];
+  av_md5_final(md5, hash);
+
+  std::copy_n(hash, std::min<size_t>(xe::countof(hash), out_size),
+              static_cast<uint8_t*>(out));
+  std::copy(std::begin(hash), std::end(hash), md5_state->buffer);
+}
+DECLARE_XBOXKRNL_EXPORT1(XeCryptMd5Final, kNone, kImplemented);
+
 // Byteswaps each 8 bytes
 void XeCryptBnQw_SwapDwQwLeBe_entry(pointer_t<uint64_t> qw_inp,
                                     pointer_t<uint64_t> qw_out, dword_t size) {